A software-defined wireless communications device, in particular a Software-Defined Radio (SDR), performs all of its signal processing in software.
Since all of the processing is performed in software, a single communications device can be used for many purposes, simply by running a different program. For example, one device can be re-programmed to be an analog cellular phone, a digital phone, a cordless home phone or even a garage door opener or baby monitor.
A software-defined wireless communications device, like the SDR, only requires software upgrades instead of expensive hardware production.
Radiation emitted by RF devices is governed by FCC regulations. To be on the safe side, the FCC typically requires that each combination of hardware and software that a radio supports be tested. The primary justification for mandating joint testing of hardware and software is that this is the only way at the present time to ensure that equipment complies with the technical standards in the FCC rules to prevent interference and to protect users from excessive RF radiation. However, there is no inherent requirement for the software of an SDR to be monolithic.
It would therefore be desirable to separate aspects of the software that do not affect RF emission of wireless devices from those aspects that are directed primarily to the signal processing functionality of the wireless device.